1. Center of Super-Diamond and Advanced Films (COSDAF); Department of Chemistry; City University of Hong Kong; Hong Kong SAR P. R. China
2. City University of Hong Kong Shenzhen Research Institute; Shenzhen 518000 P. R. China
3. Center of Super-Diamond and Advanced Films (COSDAF); Department of Physics and Materials Sciences; City University of Hong Kong; Hong Kong SAR P. R. China
4. Department of Physics and Material Sciences; City University of Hong Kong; Hong Kong SAR P. R. China